1. Field of the Invention
This invention relates generally to inflatable thermal blankets used in a medical setting to deliver a bath of a thermally-controlled gaseous medium, such as warmed air, to a patient in order to control the patient's body temperature. More particularly, the invention pertains to inflatable thermal blankets to control patient body temperature during a medical procedure while providing access through the inflated blanket for medical personnel. Still more particularly, the invention is directed to inflatable thermal blankets for use with patients receiving medical care in the lithotomy position.
2. Description of the Related Art
The inflatable thermal blanket prior art is best expressed in prior U.S. Pat. No. 4,572,188 entitled "AIRFLOW COVER FOR CONTROLLING BODY TEMPERATURE," and prior U.S. Pat. No. 5,405,371 entitled "THERMAL BLANKET". In these patents, an inflatable airflow cover (i.e., inflatable thermal blanket) is inflated by the introduction into the cover of a thermally-controlled inflating medium, such as warmed air. Holes on the underside of the inflatable thermal blanket exhaust the thermally-controlled inflating medium from inside the blanket when the blanket is placed over a patient and inflated, thereby creating an ambient environment about the patient, the thermal characteristics of which are determined by the temperature of the inflating medium. These holes open through the lower blanket surface into the blanket. The inflatable thermal blanket is intended, among other things, for the treatment of hypothermia, as might occur operatively or postoperatively.
Evaluation of inflatable thermal blankets by skilled practitioners has resulted in general approbation: the opinion is that the inflatable thermal blanket efficiently and effectively accomplishes its purpose of giving a thermally-controlled bath, and is highly effective in treating hypothermic patients. However, while the prior art inflatable thermal blanket achieves its objectives, certain improvements to it are necessary in order to realize additional clinical objectives and to enjoy further advantages in its use.
For example, one use for an inflatable thermal blanket is patient temperature control during a medical procedure, such as surgery. The patient's temperature is controlled by distributing the temperature controlled air over the patient's body. But the typical inflatable thermal blanket covers the patient's entire body and it is not possible to simultaneously access the patient, for medical purposes, while the blanket lays upon the patient and is providing temperature regulation.
The difficulty in providing patient access through an inflatable thermal blanket utilizing super atmospheric temperature controlled air is that the openings formed in the blanket necessary to provide patient access permit the temperature regulated air to escape, and such access interferes with the thermal regulation desired to be achieved by the blanket. Contamination of the procedure site because of the escaping air is also a concern.
In some medical procedures, a patient is placed in a lithotomy position. In the lithotomy position, the patient is laying on his or her back while the patient's legs are bent at the knees and extend beyond the end of the operating table. The legs are supported by "stirrups" which provide support at the knees and feet. The lithotomy position is commonly used for procedures or surgery involving the genitals or rectum, such as, for example, vaginal delivery, vaginal hysterectomy, cystoscopy (viewing the bladder with a scope), TURP--transurethral resection of the prostate, hemorrhoid and rectal surgery, nephrolithotomy (kidney stone removal) and ureteral stint placement. In the lithotomy position, the doctor is positioned between the patient's legs, having convenient access to the patient's perineal region, genitals and rectum.
Patients lose a great amount of body heat in the lithotomy position because their legs are suspended in the air and are minimally insulated. Further, some of the procedures done in this position, e.g., TURP, require the use of large volumes of irrigating fluids which also cool the patient. Moreover, many patients needing prostate surgery are older, and are therefore quite susceptible to hypothermia. It is well known in the inflatable thermal blanket art that the efficiency of heat transfer to the patient is proportional to the amount of body surface area covered by the blanket or warm air bath.
Accordingly, a need exits for an inflatable thermal blanket which is capable of delivering a temperature controlled airflow to a patient in order to maintain the patient's body temperature at a desired level while simultaneously allowing access to the patient during a medical procedure. A particular need exists for an inflatable thermal blanket that can be used with patients undergoing medical procedures while in the lithotomy position. What is required is a blanket which allows unimpaired medical access to a patient in the lithotomy position, without jeopardizing the patient's health or comfort as a result of inability to effectively control the patient's body temperature.